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that nonequilibrium processes may provide an explanation for this, particu-
larly those associated with temporal variations in lakes. Among eminent
ecologists, Gleason (
1926
), Ramensky (
1926
), and much later, Whittaker
(
1967
) were of the opinion that nonequilibria are important, and as early as
1952, von Bertalanffy concluded that living systems are open systems
characterized by a continuous flow of substances and energy across their
boundaries, that cannot establish true equilibria as found in closed systems.
Significant contributions to the establishment of what can be called
nonequilibrium ecology are provided by Andrewartha and Birch (
1954
,
1984
), and also Andrewartha (
1970
). Andrewartha and Birch, based on
their extensive and intensive studies of many natural populations, conclude
that too much emphasis on competition is fallacious. Most natural popula-
tions never become sufficiently dense to use a great proportion of the
resources that they require. Density-dependent factors and competition
therefore do not become operative (for details see p. 62).
In 1974, Levin and Paine published a seminal paper in which they
showed that disturbance increased environmental heterogeneity, pre-
venting local patches from ever achieving equilibrium, but, according
to Berryman (
1987
), the first explicit statement of the viewpoint of non-
equilibrial ecology was given by Caswell (
1978
), who said ''equilibrium
theories are restricted to behavior at or near an equilibrium point, while
nonequilibrium theories explicitly consider the transient behavior of the
system.'' This still implies the existence of equilibrium points, but systems
are rarely at or close to these points. As earlier shown experimentally
by Huffaker (
1958
) and theoretically by Maynard Smith (
1974
), spatial
dimensions can prevent a system from ''reaching a closed deterministic
solution.'' In Berryman's view, ''drawing distinctions between equilibrium
and nonequilibrium theories of populations is distracting and misleading.''
Instead, there needs to be a theory developed that would explain popula-
tion behavior both close to and far from equilibrium.
Extensive discussions of the nonequilibrium aspects of ecology are
given in Evolutionary Biology of Parasites by Price (
1980
), and in A New
Ecology. Novel Approaches to Interactive Systems edited by Price et al.(
1984
).
In the Introduction to the latter volume, Price et al.(
1984
) point out that
looking at various textbooks on ecology gives the clear impression that
interspecific competition is of great importance, whereas the opposite
view, i.e., that interspecific competition may be unimportant or only
one of several equally important processes, has found little credence.
An important reason for this unbalanced view, in the opinion of these
authors, is the fact that negative data (for example those on the absence of
